Reclosable package

ABSTRACT

This invention relates to a reclosable package including a semi-rigid receptacle and a flexible cover and an interlocking rib and groove closure strip which allows the package to be reclosable.

FIELD OF INVENTION

This invention relates to a reclosable package: and, specifically, thisinvention relates to a reclosable package for food products such ascured or sliced processed meats and cheeses where the package isevacuated and/or gas flushed and hermetically sealed.

BACKGROUND

A substantial volume of the cheese, bacon, frankfurters, sliced luncheonmeat and other processed meats are sold in packages which are formedfrom flexible thermoplastic materials. The freshness of the productwithin the package is to a large measure dependent upon the fact thatthe thermoplastic package is hermetically sealed and has been evacuatedand, in some instances, gas flushed. However, in many instances, when anevacuated package of this type is purchased not all of its contents areused at once by the consumer. When the initial seal has been broken andpart of the product removed it is difficult to reclose the package forsatisfactory storage in a refrigerator; and, in order to preserve thecontents in a fresh state without loss of flavor and texture, it isoften necessary to completely repackage the product. To overcome thisproblem, there are many prior art package designs which offer means ofopening and resealing but many of these have the disadvantage that wordyprinted directions are needed and many times the thermoplastic packagingmaterial is so stiff and so strong that even a carefully designedreclosure device can be destroyed. Thus, it is one object of the presentinvention to provide a strong, reliable means of resealing and closing athermoplastic package which has been previously vacuum sealed.

Another object of the present invention is to provide a reclosablepackage which may be made on a single machine in a straight-throughprocess rather than making a pouch on one machine and then performingthe filling, evacuating, and sealing process on another machine.

Another problem which is encountered with prior art reclosable packagesis the problem of manufacturing them at a commercially acceptable rate.Placing tear tabs, tear strips, or the like in combination withresealing means such as pressure sensitive adhesive strips calls forextreme care in registration and alignment of each of the packagingcomponents and rather precise sealing must take place in order toachieve a satisfactory product. Accordingly, another of the objects ofthe present invention is to provide a reclosable package which may bemade rapidly and reliably.

The above objects and advantages of the present invention will bereadily apparent to those skilled in the art from the description anddrawings which follow below.

DISCLOSURE STATEMENT

Below are described patents which are believed to be pertinent to thepresent disclosure.

U.S. Pat. No. 3,219,084 issued on Nov. 23, 1965 to Steven Ausnit et aland describes a method of making pouches with reclosable closure stripsby forming a pair of pouches which are initially interconnected at thetop through a double joined fastener which is subsequently severed tomake two separate bags.

U.S. Pat. No. 3,226,787 which issued to Steven Ausnit on Jan. 4, 1966describes an improved flexible closure structure for pouches and bagswherein the closure structure is formed as a flexible integral sheet oras a pair of sheets by being extruded from a single pair of die openingsshaped to form the elongated sheet with integral laterally spacedlinearly extending interlocking portions on the sheet. The interlockingfastener elements are facing each other so that they may be mated orjoined by the being pressed together without altering position.

U.S. Pat. No. 3,380,481 issued on Apr. 30, 1968 to O. K. Kraus anddescribes an elongated flexible closed one-piece tube having integrallyformed longitudinally continuous interlocking elements formed thereonfor slitting, cutting, and sealing to form closable and reusable pouchesor bags therefrom.

U.S. Pat. No. 3,473,589 issued on Oct. 21, 1969 to Waldrop O. Gotz anddescribes a closure material having flexible pressure interlockingreleasable fasteners or interlocking elements extending therealong forforming bags or similar articles for containing items such as perishablegoods.

U.S. Pat. No. 3,780,781 which issued on Dec. 25, 1973 to Tatsuro Uramotodiscloses a bag structure having strips with interlocking rib and grooveprofiles fused to the inside of the bag mouth to close the bag andadjacent reinforcing strips are provided for tear guidelines for tearingoff the top of the bag.

U.S. Pat. No. 3,784,432 which issued on Jan. 8, 1974 to Takashi Noguchidescribes a means and method of attaching a fastener profile to aplastic sheet.

U.S. Pat. No. 3,787,269 which issued on Jan. 22, 1974 to Takashi Noguchidescribes a means and method for attaching interlocking strips tolaminated sheets of plastic.

U.S. Pat. No. 3,827,472 which issued on Aug. 6, 1974 to Tatsuro Uramotodescribes a flexible bag structure with interior interlocking rib andgroove profiles to close the top of the bag with adjacent tear stripmeans to tear off the top of the bag.

U.S. Pat. No. 3,853,671 which issued on Dec. 10, 1974 to Steven Ausnitdescribes a mechanism and method for making material for multipleplastic bags with reclosable fasteners thereon.

U.S. Pat. No. Re. 28,969 which was reissued on Sept. 21, 1979 to KakujiNaito shows a reclosable plastic bag having interlocking rib and grooveelements integral with the plastic of the bag with the elements beingdesigned so that the bag opens easily from the outside but resistsopening from the inside.

U.S. Pat. No. 4,058,953 which issued on Nov. 22, 1977 to Philip A.Sanborn, Jr. describes a packaging machine for forming, evacuating, andsealing thermoplastic packages.

SUMMARY OF THE INVENTION

In one aspect, the subject invention is a reclosable package comprisingfirst and second thermoplastic sheets, at least one of which isthermoformable; and, a closure strip and a product enclosed between saidsheets by a continuous peripheral seal, the product being located insaid cavity; and, one side of said closure strip being sealed to onesheet and another side being sealed to the other sheet, each end of saidsheet terminating adjacent or in said peripheral seal so that said stripis between a portion of said peripheral seal and said product wherebywhen said portion of the peripheral seal is ruptured or cut or torn awaythe closure strip may be manually pulled apart for access to theproduct.

In another aspect, the subject invention is a reclosable package whichcomprises a product; a thermoplastic forming web having a cavity formedtherein with a peripheral flange around the opening to said cavity, saidcavity containing the product; a closure strip having one surfacethereof sealed to the forming web, said strip being adjacent andparallel to but spaced apart from one edge of the forming web, a portionof the strip at each end thereof having an indentation; and, a coveringweb sealed to the peripheral area of said forming web therebyhermetically enclosing the product and closure strip, the indentation ateach end of said strip permitting a continuous, smooth seal between saidcovering web, forming web, and closure strip in the vicinity of saidindentations.

DESCRIPTION OF THE DRAWINGS

In the drawings which are attached hereto and made a part of thisdisclosure:

FIG. 1 is a schematic representation of the apparatus which performs theprocess according to the present invention;

FIG. 2 is perspective representation of the means for forming anindentation in a closure strip according to the present invention;

FIG. 3 shows the closure strip after an indentation has been madetherein;

FIG. 4 shows a top plan view and a side view of the closure strip withthe indentation been made in the strip according to the invention;

FIG. 5 is a top plan view of a package according to the presentinvention prior to its being severed from adjacent and trailingpackages;

FIG. 6 is a cross-sectional representation of the seal bars which sealthe longitudinal center seal between the covering and forming webs andthe seal bar which seals the closure strip to the upper web;

FIG. 7 is a cross-sectional representation of an evacuation and sealingstation showing the position of the seal bars of FIG. 6 with respect tothe filled forming web cavities of the package of the present invention;

FIG. 8 is a cross-sectional representation of a portion of the packageof the present invention showing the arrangement of the seals orenclosure strips prior to packages being severed one from the other;

FIG. 9 is a cross-sectional representation of a closure strip showingthe strip sealing perforations or scores in the covering web; and,

FIG. 10 is a perspective view of a package according to the presentinvention.

DETAILED DESCRIPTION

Referring principally to FIG. 1, the apparatus and process of thesubject invention will be described as well as the package which theprocess and apparatus produce. The closure strip 1 which provides thereclosable feature of the package of the present invention is suppliedfrom supply roll 2 and is advanced or fed to the closure die punchassembly 3. This assembly and the punching performed at this station canbe better appreciated by viewing FIGS. 2, 3, and 4 where punches 18 areshown in position to punch out the indentation 19 in the closurestrip 1. In FIG. 2 the punching operation has just begun and in FIG. 3the punching step has been completed and the result of the punching orstrip removal can be better appreciated by reference to the top planview in FIG. 4 of the closure strip.

The closure strip as shown is a double strip which supplies the closureelement of strip 1 for two or more packages. The strip 1 comprises themale or rib portion 17 which interlocks into the female or groovedportion 16. As shown, there are two interlocking ribs which extendlongitudinally on the rib portion 17 which snap fit into thecorresponding longitudinal grooves on the groove or female portion 16.The present invention is not limited to any particular number ofinterlocking ribs and grooves as satisfactory closure strips can be madewith one rib and one groove or with a plurality of ribs and grooves. Themain criteria are that the rib and groove portions of the closure stripbe readily separable by the fingers of the consumer who has purchasedthe package and that they be readily reclosable.

Still referring to FIGS. 2, 3, and 4 it should be noted that the grooveportion or element 16 of the closure strip has a flange which isintegral with the top surface of the closure strip and this provides foradditional seal surface area between the groove 16 and the covering webor upper thermoplastic film. The flange which connects the ribbedportions 17 of the closure strip also provides a larger seal surface forsealing to the forming web or lower thermoplastic film in addition toconnecting the two segments of the closure strip. It should beunderstood, of course, that the present invention could be practicedwithout having two connected closure strips but for ease in productionand assembly it is economical to use the two side-by-side connectedclosure strips so that two or more packages can be made at the sametime. Furthermore, there is no necessity for the rib portion to be onthe lower closure strip segment or on the upper segment as the closurestrip will function properly either way.

As shown in FIG. 2 the flange portion of the upper segment of theclosure strip 1 has been folded over by a folding shoe which is notshown so that the punches 18 can punch out the entire upper flange andentire interlocking elements in one stroke and still leave enoughmaterial in the lower flange so that the strip will not be too weakenedand break as it is advanced toward the forming web. The purpose formaking the indentation or punch out in the closure strip is so that asmooth, fast, and secure peripheral seal can be made for the package aswill be more fully described hereinafter.

Returning now to FIG. 1, the closure strip is advanced from the diepunch assembly 3 to the closure strip seal station 4 where it meets thefirst thermoplastic sheet or forming web 5 which is fed and advancedfrom supply roll 6 through registration station 7 past a pair ofperforating scoring wheels 35 and over a roller to meet the closurestrip 1 at the closure strip seal station 4. Both the closure strip 1and the forming web 5 are made from thermoplastic materials with theclosure strip preferably being made from polyethylene or an ionomer andthe forming web being thermoformable and preferably being a laminate ofnylon and polyethylene which laminate in some instances will havemultiple layers of these materials and, in addition may have a gasbarrier layer or layers from material such as saran or hydrolyzedethylene-vinyl acetate copolymer. The closure strip 1 is heat sealed tothe forming web at the seal station and the sealing means can be eithera plate and roller whereby the roller presses the strip against theheated plate as the closure strip 1 and forming web 5 pass thereover ora heated roller can press the strip or sheet against a backing surface.Another and preferred means of sealing is to use the combination of aheated plate and backing plate and when the motion of the sealing stripand forming web is stopped the web and strip are pressed togetherbetween said plates whereby the seal is completed during the stop. Bothcontinuous sealing and intermittent between two thermoplastic surfacesis well known and within the skill of the art.

The closure strip is sealed over the score line or perforations 36 inthe forming web 5 as shown in cross-section in FIG. 9. The score linesor perforations 36 were placed in the film web 5 by the scoring orperforating wheels 35 whose position is shown in FIG. 1. This pair ofwheels (only one is visible in FIG. 1) simply punch out two lines ofsmall holes in the forming web as the web passes between them and thebacking roller, one line of perforations being made for each package.Instead of perforating wheels which punch holes in the web, scoringwheels may be used which "score" or press or cut a score line which cutsinto the surface of the web but does not cut completely through the web.This score line may be continuous or intermittent.

Referring again to FIG. 1, after the closure strip has been sealed tothe forming web at station 4 the forming web moves to forming station 8where cavities or pockets are formed in the forming web. The forming webis first clamped around the periphery of the forming die cavity, heatedto its forming temperature and drawn by pressure differential into thedie cavity where it is formed and cooled. In FIG. 7 the cross-section ofthe evacuation and sealing station 38 is shown and the pocket 28 closelyresembles a forming cavity at forming station 8. The pressuredifferential is applied through the ports 40 to draw the forming webinto the cavity for thermoforming. In FIG. 7 the position of the closurestrip 1 at the sealing station is also shown. At this point the formedpockets 9 have been made and the closure strip 1 is securely sealed tothe forming web in the area between the pair of pockets 9 as can be seenin FIG. 9.

After leaving the forming station 8 as shown in FIG. 1, the pockets aremoved to loading station 10 where the product is placed in the pockets.Almost any type of product can be packaged but specifically the presentinvention is intended for food products such as sliced meat productsincluding bacon and sliced breakfast meats, luncheon meats, cheeses andthe like.

After the product has been loaded into the pockets, the loaded pocket isthen advanced to meet the second thermoplastic sheet or covering web 11which is fed from covering web supply roll 12 and passes through a webregistration station 13 on its way to be laid over the pockets toenclose the product and closure strip between the first and secondthermoplastic sheets. The covering web is also a thermoplastic sheet,preferably a nylon or polyester/polyethylene laminate, but of lightergauge than the forming web so that it is not generally considered to bea formable film because it will not readily extend. The covering webalso may include a layer of gas barrier material such as saran orhydrolyzed ethylene vinyl acetate copolymer and may be printed with thelabel of the particular packer. The polyethylene or ethylene vinylacetate copolymer layers generally serve as sealing layers and sometimesan ionomer may be used for these layers.

When laid over the pockets filled with product 29, the covering web 11covers the pockets as shown in FIG. 7. This assembly as shown in FIG. 7in cross-section is the sealing and gas flushing and evacuation station38 where the final package seals are to be made. The peripheral sealsare made along the area 41 and the center seal is made between thepockets. While in the station 38 the webs are clamped together betweenouter wall 42 and pocket 28 generally in the area 41. The space betweenthe two webs 5 and 11 which contains the product in the cavity 9 may beevacuated in any one of many different ways and the present invention isnot to be limited to any particular method of evacuating the package asmany are available in the prior art. Actually, the evacuation or gasflushing station 38 is really a vacuum chamber and in some methods thewebs may be kept separated by either applying a vacuum above coveringweb 11 at the same time that vacuum is applied through ports 40 to theforming web to separate the two webs so that they may be evacuatedthrough the separation. in other designs the peripheral area 41 may becompletely sealed and then the upper web 11 is drawn against a vacuumport containing a knife to slit the upper film 11 so that the packagemay be evacuated through the slit before the slit is resealed. In thepreferred design as shown, the upper web 11 is pre-slit to serve as anevacuation port (see arrows indicating flow of air) and this pre-slitweb is then finally sealed by a seal bar 30 when the center seal ismade. In any event, after the evacuation of the package is completed andgas filled, if desired, the final sealing takes places and is shown ingreater detail in FIG. 6 where resilient seal member 39 serves as thebacking pad for the seal bar 30. At this point the lower or forming web5 has already been sealed to closure strip 1 and as the seal bar 30 islowered the peripheral seal is made closing the evacuation slit (seeFIG. 7) and the center seal bar face makes the main center seal betweenthe packages as it is pressed downwardly while the closure strip sealbar face 32 seals the upper surface of the closure strip 1 to the upperor covering web 11. When this sealing step has been accomplished thecross section in an exploded fashion of the area shown in FIG. 6 can beseen better by looking at FIG. 8. The center seal 25 is shown where theupper web 11 is sealed to the flange between the closure elements andthe closure elements on the closure strip are sealed to the lower web 5.Center line 21 notes the cut line between the packages and the line 32is the line along which the package can be cut or if a score line orperforations are placed along this line (see FIG. 9) such as theperforations 36 then the package can be torn open along this line. Thisremoves the outer hermetic seal and exposes the closure strip to manualopening by gripping each severed flange and pulling the closure stripsapart. After they have been pulled apart they may be readily pressedtogether for resealing.

A top plan view of a package with one end having been trimmed by cutter14 (see FIG. 1) so that vacuum 37 carries away the trimmed portions isshown in FIG. 5 and the longitudinal cut line 21 is shown as well as thetransverse cut line 22 between package seals. A tear tab notch 27 may beprovided in which the line of perforations terminates or a slit may besubstituted for the notch. This provides the starting point for a tearline to tear along the perforations 36 which are not shown in FIG. 5 butwhich are shown in their proper positions in FIG. 9. The top of theclosure elements 16 as shown in FIG. 5 and the peripheral seal 24 whichis the longitudinal outside edge seal is also shown along with thetransverse seal 23 between each package. The indentation 19 for eachpackage seal is shown and as can be seen the indentation 19 provides fora smooth continuous transverse seal. If the indentation 19 were notprovided then the continuous closure strip in this area would present alarge mass of material which would have to be melted and pressed down atthis point in order to ensure that complete sealing was achieved. Toapply sufficient energy to melt this mass of material in a short periodof time would require is impractical and to hold the seal bars in adwell position that for a sufficient period of time in order to melt theseal would require a very slow process. By providing an indented closurestrip these sealing problems are avoided.

As a practical matter it is more economical to continuously manufacturethe sealing strip and then indent or punch out the unnecessary portions.However, in some instances it might be feasible to manufacture theindentations in the closure strip but, if this were done, it would limitsuch a closure strip to a certain length package whereas in the processof this invention the punch may be timed to punch at the exact pocketlength. The pocket outline 26 shown in FIG. 5 can be varied in anymachine by using appropriate dies.

The finished package 15 has an appearance as shown in FIG. 10 and thispackage may be readily reopened and resealed.

Having thus described my invention I claim:
 1. A reclosable packagecomprising:(a) a product; (b) a semi-rigid, thermoplastic forming webhaving a cavity formed therein with a peripheral flange having acontinuous sealing surface around the opening to said cavity, saidcavity containing said product; (c) a separable reclosable, flexible,thermoplastic two part interlocked closure strip with each partcomprising longitudinal, interlocking rib and groove elements and eachpart having a sealing surface with one sealing surface thereof sealed tosaid sealing surface of said forming web, said strip being adjacent andparallel to but spaced apart from one edge of the forming web, saidstrip extending substantially the length of said edge, and a portion ofthe strip at each end thereof having an indentation; and, (d) a flexiblecovering web sealed by a peripheral heat seal to the sealing surface ofthe peripheral flange of said forming web hermetically enclosing theproduct and closure strip, said covering web being sealed to the othersealing surface of said closure strip, the indentation at each end ofsaid strip permitting each end of said closure strip to terminate in theperipheral seal in a continuous, smooth seal between said covering web,forming web, and closure strip whereby said hermetically sealed packagemay be opened from one side by severing or tearing the covering orforming web or both between said closure strip and adjacent peripheralseal and thereafter separating the closure strip parts to gain access tothe product.
 2. The reclosable package of claim 1 wherein said formingweb includes a series of perforations therein to form a tear lineparallel to said closure strip, said perforations being sealed by aportion of said closure strip.
 3. The reclosable package of claim 2wherein each end of said tear line terminates in a notch in the sealedperipheral area in opposite sides of said package.
 4. The reclosablepackage of claim 3 wherein said indentations are punched out portions ofsaid closure strip.